Hi, I have a simple question (well, at least I think it's simple!). I have a router, with four Ethernet cards; eth0-eth3. eth0 and eth3 are the 'external' cards, connecting to my ISPs. eth1 and eth2 are connected to my internal networks. What I want to do is basically filter all the traffic from one card to another, in this configuration: eth1 to eth3 eth2 to eth0 The thing is, I'm not sure if this is a routing or a firewall problem, or maybe a bit of both? I've tried setting up the routing using ip route, using the command below, but to no avail. When I used these commands, I did not change any of my existing firewall configuration. Here are the ip route commands: echo "101 ISP_1" >> /etc/iproute2/rt_tables echo "102 ISP_2" >> /etc/iproute2/rt_tables ip route add 192.168.4.0/22 dev eth2 src 192.168.7.253 table ISP_1 ip route add default via 192.168.100.253 table ISP_1 ip route add 192.168.0.0/22 dev eth1 src 192.168.3.253 table ISP_2 ip route add default via 192.168.20.253 table ISP_2 ip rule add from 192.168.7.253 table ISP_1 ip rule add from 192.168.3.253 table ISP_2 I also tried a simple iptables forward command, in the form of: iptables -A FORWARD -i eth0 -o eth2 -j ACCEPT iptables -A FORWARD -i eth2 -o eth0 -j ACCEPT iptables -A FORWARD -i eth1 -o eth3 -j ACCEPT iptables -A FORWARD -i eth3 -o eth1 -j ACCEPT # default policy iptables -P FORWARD DROP In both cases, I have set /proc/sys/net/ipv4/ip_forward to "1". Any help would be greatly appreciated. Many thanks, Paul --- Paul Lewis (paul.lewis@xxxxxxxxxxxxxxxxx) Part II Student Materials Science University of Oxford
